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Date:   Thu, 15 Jun 2023 19:34:26 +0200
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From:   Johan Jonker <jbx6244@gmail.com>
Subject: [PATCH v3 3/3] mtd: rawnand: rockchip-nand-controller: add skipbbt
 option
To:     miquel.raynal@bootlin.com
Cc:     richard@nod.at, vigneshr@ti.com, heiko@sntech.de,
        linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-rockchip@lists.infradead.org, yifeng.zhao@rock-chips.com
References: <0047fc52-bc45-a768-8bdd-c0f12cddc17e@gmail.com>
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On Rockchip SoCs the first boot stages are written on NAND
with help of manufacturer software that uses a different format
then the MTD framework. Skip the automatic BBT scan with the
NAND_SKIP_BBTSCAN option so that the original content is unchanged
during the driver probe.
The NAND_NO_BBM_QUIRK option allows us to erase bad blocks with
the nand_erase_nand() function and the flash_erase command.
With these options the user has the "freedom of choice" by neutral
access mode to read and write in whatever format is needed.

Signed-off-by: Johan Jonker <jbx6244@gmail.com>
---

Changes V3:
  Change prefixes

Changed V2:
  reword

---

I'm aware that the maintainer finds it "awful",
but it's absolute necessary to:
1: read/write boot blocks in user space without touching original content
2: format a NAND for MTD either with built in or external driver module

So we keep it include in this serie.
---
 drivers/mtd/nand/raw/rockchip-nand-controller.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/mtd/nand/raw/rockchip-nand-controller.c b/drivers/mtd/nand/raw/rockchip-nand-controller.c
index 5a0468034..fcda4c760 100644
--- a/drivers/mtd/nand/raw/rockchip-nand-controller.c
+++ b/drivers/mtd/nand/raw/rockchip-nand-controller.c
@@ -188,6 +188,10 @@ struct rk_nfc {
 	unsigned long assigned_cs;
 };

+static int skipbbt;
+module_param(skipbbt, int, 0644);
+MODULE_PARM_DESC(skipbbt, "Skip BBT scan if data on the NAND chip is not in MTD format.");
+
 static inline struct rk_nfc_nand_chip *rk_nfc_to_rknand(struct nand_chip *chip)
 {
 	return container_of(chip, struct rk_nfc_nand_chip, chip);
@@ -1153,6 +1157,9 @@ static int rk_nfc_nand_chip_init(struct device *dev, struct rk_nfc *nfc,

 	nand_set_controller_data(chip, nfc);

+	if (skipbbt)
+		chip->options |= NAND_SKIP_BBTSCAN | NAND_NO_BBM_QUIRK;
+
 	chip->options |= NAND_USES_DMA | NAND_NO_SUBPAGE_WRITE;
 	chip->bbt_options = NAND_BBT_USE_FLASH | NAND_BBT_NO_OOB;

--
2.30.2